The point was that if you only need to train once, then it's cheaper to rent the GPUs than to buy them. If you need to train it multiple times, then the cost of buying the GPUs is amortized among runs.
In any case the cost per run is going to be lower than 30m
I'm sure that's the case. The latest sku I'm responsible for QC testing now contains 4x A100's in a 2U chassis. And oh man the number of QSFP ports it utilizes..